There are several different types of hearing aid styles widely known in the hearing aid industry and described with the following designations: behind-the-ear (BTE), in-the-ear or all in-the-ear (ITE), in-the-canal (ITC), and completely-in-the-canal (CIC).
Hearing aid technology has progressed rapidly in recent years. Technological advancements in this field continue to improve the reception, wearing-comfort, life-span, and power efficiency of hearing aids. However, even with these continual advances in the performance of hearing aids, there is still a continuous demand for improving the performance of the miniature acoustic transducers that are utilized in hearing aids and other similar applications. Therefore, disclosure will be directed primarily at hearing aid transducers in addition to miniature transducers in general.
A listening device, such as a hearing aid, includes a microphone, an amplifier and a transducer (also commonly referred to as a “receiver” or simply, a “speaker”). The microphone receives acoustic sound waves and creates an electronic signal representative of these sound waves. The amplifier accepts the electronic signal, modifies the electronic signal, and communicates the modified electronic signal (e.g. processed signal) to the transducer. The transducer, in turn, converts the processed electronic signal into acoustic energy for transmission to the user's ear.
Conventionally, a hearing aid transducer includes a housing, a sound outlet port, an electrical terminal, at least one diaphragm, a magnet assembly, and a motor assembly. The magnet assembly includes a magnetic yoke and a pair of drive magnets attached to the magnetic yoke. The motor includes an armature, at least one linkage assembly, a drive coil, and a lead connecting the coil to the terminal. When an alternating current is supplied to the coil via the terminal, the armature vibrates in response to the magnetic field generated by the motor assembly. The vibration of the armature is transmitted via the linkage assembly to the diaphragm, which causes sound vibrations that are transmitted to the user.
Conversely, sound vibrations vibrate the diaphragm causing the armature to vibrate via the linkage assembly. This vibration generates an electric alternating current in the coil. The electrical signal is then transmitted out through the terminal, detected and processed accordingly.
Typically the linkage assembly connecting the armature and the diaphragm may be of a motion-redirection type disclosed in U.S. patent application Ser. No. 09/755,664, which is a continuation-in-part of U.S. patent application Ser. No. 09/479,134, now abandoned, U.S. patent application Ser. No. 10/719,809, U.S. patent application Ser. No. 10/719,765, U.S. patent application Ser. No. 10/842,654 and U.S. patent application Ser. No. 10/842,663, the disclosures of which are all incorporated herein by reference.
The motion-redirection linkage is usually a four-sided or a six-sided linkage assembly supported by a pair of upright supporting members. The linkage assembly includes an upper portion and a lower portion each having a plurality of link members that transmit motion to the diaphragm in response to that of the armature. The motion of the diaphragm will be equal and opposite to that of the armature if the upper portion of the link is identical in shape and size as the lower portion of the link.
However, the sound pressure output is limited by the area and displacement of the diaphragm and the displacement of the diaphragm is limited by the motor assembly including the armature and the linkage. Attempts to increase the displacement of the diaphragm to amplify this sound cause unwanted distortion.
Therefore, there is a need for an improved transducer which incorporates a linkage design that can amplify the sound output of the diaphragm without causing substantial distortion. Methods for amplifying diaphragm output are also needed that compensate for or counteract distortions generated by such attempts at amplification.
Further, there is a need for improved transducers used in receivers, microphones, speakers, accelerometers, Micro-Electro-Mechanical Systems (MEMS) devices or any other device where motion amplification is desirable.
The drawings are not necessarily to scale and the disclosed embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details in the drawings may have been omitted which are not necessary for an understanding of the disclosed linkage assemblies or the methods of amplifying the output of the transducers using the linkage assemblies while compensating for distortion. It should be understood that this disclosure is not limited to the particular embodiments illustrated in the drawings and disclosed herein. In short, numerous modifications will be apparent to those skilled in the art which fail within the spirit and scope of this disclosure and the appended claims.